The Experts below are selected from a list of 186 Experts worldwide ranked by ideXlab platform

Stephen P. Robinson - One of the best experts on this subject based on the ideXlab platform.

  • Developments in standards and calibration methods for hydrophones and Electroacoustic Transducers for underwater acoustics.
    Journal of the Acoustical Society of America, 2014
    Co-Authors: Stephen P. Robinson, Kenneth G. Foote, Pete D. Theobald
    Abstract:

    If they are to be meaningful, underwater acoustic measurements must be related to common standards of measurement. In this paper, a description is given of the existing standards for the calibration of hydrophones and Electroacoustic Transducers for underwater acoustics. The description covers how primary standards are currently realized and disseminated, and how they are validated by international comparisons. A report is also given of the status of recent developments in specification standards, for example within the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). The discussion focuses on the revision of standards for transducer calibration, and the inclusion of extended guidance on uncertainty assessment, and on the criteria for determining the locations of the acoustic near-field and far-field. A description is then provided of recent developments using non-traditional techniques such as optical sensing, which may lead to the next generat...

  • developments in standards and calibration methods for hydrophones and Electroacoustic Transducers for underwater acoustics
    Journal of the Acoustical Society of America, 2014
    Co-Authors: Stephen P. Robinson, Kenneth G. Foote, Pete D. Theobald
    Abstract:

    If they are to be meaningful, underwater acoustic measurements must be related to common standards of measurement. In this paper, a description is given of the existing standards for the calibration of hydrophones and Electroacoustic Transducers for underwater acoustics. The description covers how primary standards are currently realized and disseminated, and how they are validated by international comparisons. A report is also given of the status of recent developments in specification standards, for example within the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). The discussion focuses on the revision of standards for transducer calibration, and the inclusion of extended guidance on uncertainty assessment, and on the criteria for determining the locations of the acoustic near-field and far-field. A description is then provided of recent developments using non-traditional techniques such as optical sensing, which may lead to the next generation of standards. A report is also given of the status of recent developments in and of a number of current initiatives to promote best measurement practice.

  • Calibration of hydrophones and Electroacoustic Transducers: A contribution to the OES standards initiative
    OCEANS 2014 - TAIPEI, 2014
    Co-Authors: Stephen P. Robinson, Pete D. Theobald, Kenneth G. Foote
    Abstract:

    Underwater acoustic measurements are made to provide validation and qualification for a wide range of applications and developments in the off-shore industry, oceanography, defense, fisheries, and geophysics. However, measurements are only meaningful if they are performed in a technically sound manner and if they can be related to common standards of measurement. In this paper, a summary is given of the existing standards for hydrophones and Electroacoustic Transducers used in underwater acoustics. A description is given of how primary standards are currently realized and disseminated, how they are validated by international comparisons, and of new developments which may lead to the next generation of standards. A report is also given of the status of recent developments in specification standards, for example, within the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). Finally, a description is provided of the current initiative within the Oceanic Engineering Society (OES) to compile and disseminate information on standards, protocols, quality assurance (QA) procedures, and best practices that are important in ocean engineering.

  • A model for characterizing the frequency-dependent variation in sensitivity with temperature of underwater acoustic Transducers from historical calibration data
    Measurement Science and Technology, 2007
    Co-Authors: Peter M. Harris, Stephen P. Robinson, Gary Hayman, G.a. Beamiss, T J Esward, I M Smith
    Abstract:

    The performance of underwater Electroacoustic Transducers often depends on water temperature and, for accurate calibrations, it is necessary to take account of this influence on measurement data. Doing so is particularly important for open-water calibration facilities where the environmental conditions cannot be controlled and seasonal variations in temperature can contribute significant measurement uncertainty. This paper describes the characterization of the sensitivity of underwater Electroacoustic Transducers in terms of their variation with water temperature. A model containing adjustable parameters is developed for providing frequency-dependent temperature coefficients whose use enables measurement data to be corrected for temperature. Estimates of these coefficients are determined by applying the model to the time history of measurement data obtained over a period of several years. The influence of seasonal temperature variation can then be separated from the slow temporal drift in the transducer sensitivity. The uncertainties associated with the corrected sensitivity values are evaluated.

  • the application of wavelets and other techniques to the calibration of underwater Electroacoustic Transducers in reverberant laboratory tanks
    2001
    Co-Authors: P M Harris, Gabriel J Lord, I M Smith, Stephen P. Robinson
    Abstract:

    In the calibration of underwater electracoustic Transducers undertaken in reverberant laboratory tanks, data processing is used to extract from the measured data the required information for the calibration. This information is the voltage that would be measured in the absence of contaminating effects, including transients due to the resonance of the devices, reflections of the transmitted signal, and noise. There are a number of approaches to performing the data analysis currently in use, including the application of signal processing techniques based on Fourier analysis as well as regression modelling. Wavelet analysis provides another approach to analysing spectrally varying sequences of data that complements the traditional Fourier analysis. Wavelets provide a general set of basis functions that are localised both in time and frequency, and wavelet analysis has been applied successfully to problems in feature recognition, signal compression, function representation and as a basis for numerical schemes. The coefficients obtained in a wavelet expansion are useful as they relate directly to a time (or place) and frequency, and to the smoothness of the signal. In this report we provide a summary of some of the 'traditional' data analysis methods used for the calibration of underwater Electroacoustic Transducers, and indicate some of their limitations. We then give a brief introduction to wavelet analysis, and consider how methods of analysis based on wavelets can be applied to this particular measurement problem. The intention here is to consider how wavelet analysis may support and complement the 'traditional' methods of analysis by addressing some of the limitations of those methods.

Catherine Dehollain - One of the best experts on this subject based on the ideXlab platform.

  • In-vitro platform to study ultrasound as source for wireless energy transfer and communication for implanted medical devices
    2010 Annual International Conference of the IEEE Engineering in Medicine and Biology, 2010
    Co-Authors: Francesco Mazzilli, Michela Peisino, Rostand Mitouassiwou, Benjamin Cotté, Prakash Thoppay, Cyril Lafon, Patrick Favre, Eric Meurville, Catherine Dehollain
    Abstract:

    A platform to study ultrasound as a source for wireless energy transfer and communication for implanted medical devices is described. A tank is used as a container for a pair of Electroacoustic Transducers, where a control unit is fixed to one wall of the tank and a transponder can be manually moved in three axes and rotate using a mechanical system. The tank is filled with water to allow acoustic energy and data transfer, and the system is optimized to avoid parasitic effects due to cables, reflection paths and cross talk problems. A printed circuit board is developed to test energy scavenging such that enough acoustic intensity is generated by the control unit to recharge a battery loaded to the transponder. In the same manner, a second printed circuit board is fabricated to study transmission of information through acoustic waves.

John L Butler - One of the best experts on this subject based on the ideXlab platform.

  • Transducers and Arrays for Underwater Sound
    2020
    Co-Authors: Charles H Sherman, John L Butler
    Abstract:

    This book is concerned with the theory, development and design of Electroacoustic Transducers for underwater applications, and is more comprehensive than any existing book in this field. It includes the basics of the six major types of Electroacoustic Transducers, with emphasis on the piezoelectric ceramic Transducers that are currently most widely used. It presents the basic acoustics, as well as specific acoustic data, needed in transducer design and includes analysis of nonlinear effects in Transducers. A large number of specific transducer designs, including both projectors and hydrophones, are described in detail as well as methods of modeling, evaluation and measurement. Analysis of transducer arrays, including the effects of mutual radiation impedance, as well as numerical models for Transducers and arrays are also covered. The book contains an extensive Appendix of useful current information, including data on the latest transduction materials, and numerous diagrams that will facilitate its use by students and practicing engineers and scientists

  • Transducers and Arrays for Underwater Sound
    2008
    Co-Authors: Charles H Sherman, John L Butler
    Abstract:

    The subject of this book is the theory, development and design of Electroacoustic Transducers for underwater applications. It is more comprehensive than any existing book in this field. It includes the basics of the six major types of Electroacoustic Transducers and shows why piezoelectric ceramic Transducers are the most suitable for underwater sound. It presents the basic acoustic concepts and models needed in transducer and transducer array development, and discusses most currently used transducer designs. It analyzes nonlinear effects and describes methods of transducer evaluation and measurement. The extensive Appendix and numerous diagrams provide an up to date source for use by students and practicing engineers and scientists. A complete set of exercises and solutions from the book are currently available on the Springer website.

  • analysis of harmonic distortion in Electroacoustic Transducers under indirect drive conditions
    Journal of the Acoustical Society of America, 1997
    Co-Authors: Charles H Sherman, John L Butler, Alexander L Butler
    Abstract:

    Nonlinear transducer equations for the six major types of Electroacoustic Transducers (electrostatic, variable reluctance, moving coil, piezoelectric, electrostrictive, and magnetostrictive) are formulated in a common way and solved approximately by perturbation analysis for indirect drive, i.e., current drive of electric field Transducers and voltage drive of magnetic field Transducers. The direct drive analysis, i.e., voltage drive of electric field Transducers and current drive of magnetic field Transducers, was given in J. Acoust. Soc. Am. 98, 1596–1611 (1995). Expressions and graphs are given for some of the indirect drive harmonics which apply to all six transducer types. The solutions for direct and indirect drive are compared, and some of the differences are discussed with emphasis on the question of which drive gives lower harmonic distortion. No answer to this question has been found that is applicable to all nonlinear mechanisms in all Transducers at all frequencies. However, it is shown that f...

  • analysis of harmonic distortion in Electroacoustic Transducers
    Journal of the Acoustical Society of America, 1995
    Co-Authors: Charles H Sherman, John L Butler
    Abstract:

    Nonlinear transducer equations are formulated for the six major types of Electroacoustic Transducers (electrostatic, variable reluctance, moving coil, piezoelectric, electrostrictive, and magnetostrictive) in a common form using the various physical and mathematical similarities among the transduction mechanisms. The common nonlinear equation is solved approximately by perturbation analysis giving simple expressions and graphs for harmonic amplitudes caused by all the frequently occurring nonlinear mechanisms. The expressions and graphs can be applied to all the transducer types by using nonlinear parameters tabulated for each type. These results can facilitate diagnosis of the cause of measured harmonics, prediction of harmonics during design, and development of electrical drives to suppress harmonics.

  • nonlinear behavior of Electroacoustic Transducers
    Journal of the Acoustical Society of America, 1994
    Co-Authors: Charles H Sherman, John L Butler
    Abstract:

    An important goal of Electroacoustic transducer development has long been maximization of the acoustic output power for a given transducer size. This goal always encounters familiar material mechanical, electrical, magnetic or thermal limitations—all the ultimate effects of nonlinear behavior. However, other nonlinear effects, such as harmonic distortion and instability, are the practical operational limitation in some applications, making nonlinear analysis an essential part of the process. Most basic transduction mechanisms are strongly nonlinear and all have some nonlinearities. Fortunately, the nonlinearities in all Transducers have similar features and can often be represented in identical mathematical forms even when physically different. This study identifies the nonlinear features which are common to all major types of Transducers (electrostatic, variable reluctance, piezoelectric, electrostrictive, magnetostrictive, and moving coil). Recognizing these common features makes it possible to develop ...

P M Harris - One of the best experts on this subject based on the ideXlab platform.

  • the application of wavelets and other techniques to the calibration of underwater Electroacoustic Transducers in reverberant laboratory tanks
    2001
    Co-Authors: P M Harris, Gabriel J Lord, I M Smith, Stephen P. Robinson
    Abstract:

    In the calibration of underwater electracoustic Transducers undertaken in reverberant laboratory tanks, data processing is used to extract from the measured data the required information for the calibration. This information is the voltage that would be measured in the absence of contaminating effects, including transients due to the resonance of the devices, reflections of the transmitted signal, and noise. There are a number of approaches to performing the data analysis currently in use, including the application of signal processing techniques based on Fourier analysis as well as regression modelling. Wavelet analysis provides another approach to analysing spectrally varying sequences of data that complements the traditional Fourier analysis. Wavelets provide a general set of basis functions that are localised both in time and frequency, and wavelet analysis has been applied successfully to problems in feature recognition, signal compression, function representation and as a basis for numerical schemes. The coefficients obtained in a wavelet expansion are useful as they relate directly to a time (or place) and frequency, and to the smoothness of the signal. In this report we provide a summary of some of the 'traditional' data analysis methods used for the calibration of underwater Electroacoustic Transducers, and indicate some of their limitations. We then give a brief introduction to wavelet analysis, and consider how methods of analysis based on wavelets can be applied to this particular measurement problem. The intention here is to consider how wavelet analysis may support and complement the 'traditional' methods of analysis by addressing some of the limitations of those methods.

  • modelling acoustic signals in the calibration of underwater Electroacoustic Transducers in reverberant laboratory tanks
    1999
    Co-Authors: S P Robinson, P M Harris
    Abstract:

    In the calibration of an underwater Electroacoustic transducer, the stepped-sinusoidal signals that are commonly used are contaminated by transients due to the resonant behaviour of the transducer, as well as noise. In addition, when calibrations are undertaken in reverberant laboratory tanks of finite size, reflections from the tank boundaries often arrive before the steady-state response of the transducer can be observed directly. However, by use of suitable signal models, it is possible to predict the steady-state response from the initial transient-dominated part of the waveform. The approach considered here is to model the free-time response of the device by a function consisting of a sum of complex exponential terms which are used to describe both the steady-state and resonant behaviour of the device. In this report, we review two classes of estimation method: linear prediction methods (such as Prony’s method and its variants), and nonlinear least-squares methods. Standard linear prediction methods are shown to be statistically biased and inefficient. This observation motivates the development of a linear prediction method in which proper account is taken of the error structure in the data. A nonlinear least-squares algorithm is also described based on a safeguarded Gauss-Newton algorithm that uses regularisation to address the ill-conditioning that is a property of the underlying problem. Results are presented of using these methods to analyse simulated data generated to represent the measured response of a device. The effect of varying in a systematic manner the properties of the simulated data and device under test is investigated. Results are also presented for data obtained from measurements of a real transducer, and it is shown how these results may be used to establish the free-field sensitivity of the device. Finally, results are presented of using the information gained from the modelling of the transducer resonant behaviour to predict the transducer frequency response at frequencies other than those under test. This report constitutes the deliverable of project 2.1d(ii) of the 1995-98 NMS Acoustics Metrology Programme.

Charles H Sherman - One of the best experts on this subject based on the ideXlab platform.

  • Transducers and Arrays for Underwater Sound
    2020
    Co-Authors: Charles H Sherman, John L Butler
    Abstract:

    This book is concerned with the theory, development and design of Electroacoustic Transducers for underwater applications, and is more comprehensive than any existing book in this field. It includes the basics of the six major types of Electroacoustic Transducers, with emphasis on the piezoelectric ceramic Transducers that are currently most widely used. It presents the basic acoustics, as well as specific acoustic data, needed in transducer design and includes analysis of nonlinear effects in Transducers. A large number of specific transducer designs, including both projectors and hydrophones, are described in detail as well as methods of modeling, evaluation and measurement. Analysis of transducer arrays, including the effects of mutual radiation impedance, as well as numerical models for Transducers and arrays are also covered. The book contains an extensive Appendix of useful current information, including data on the latest transduction materials, and numerous diagrams that will facilitate its use by students and practicing engineers and scientists

  • Transducers and Arrays for Underwater Sound
    2008
    Co-Authors: Charles H Sherman, John L Butler
    Abstract:

    The subject of this book is the theory, development and design of Electroacoustic Transducers for underwater applications. It is more comprehensive than any existing book in this field. It includes the basics of the six major types of Electroacoustic Transducers and shows why piezoelectric ceramic Transducers are the most suitable for underwater sound. It presents the basic acoustic concepts and models needed in transducer and transducer array development, and discusses most currently used transducer designs. It analyzes nonlinear effects and describes methods of transducer evaluation and measurement. The extensive Appendix and numerous diagrams provide an up to date source for use by students and practicing engineers and scientists. A complete set of exercises and solutions from the book are currently available on the Springer website.

  • analysis of harmonic distortion in Electroacoustic Transducers under indirect drive conditions
    Journal of the Acoustical Society of America, 1997
    Co-Authors: Charles H Sherman, John L Butler, Alexander L Butler
    Abstract:

    Nonlinear transducer equations for the six major types of Electroacoustic Transducers (electrostatic, variable reluctance, moving coil, piezoelectric, electrostrictive, and magnetostrictive) are formulated in a common way and solved approximately by perturbation analysis for indirect drive, i.e., current drive of electric field Transducers and voltage drive of magnetic field Transducers. The direct drive analysis, i.e., voltage drive of electric field Transducers and current drive of magnetic field Transducers, was given in J. Acoust. Soc. Am. 98, 1596–1611 (1995). Expressions and graphs are given for some of the indirect drive harmonics which apply to all six transducer types. The solutions for direct and indirect drive are compared, and some of the differences are discussed with emphasis on the question of which drive gives lower harmonic distortion. No answer to this question has been found that is applicable to all nonlinear mechanisms in all Transducers at all frequencies. However, it is shown that f...

  • analysis of harmonic distortion in Electroacoustic Transducers
    Journal of the Acoustical Society of America, 1995
    Co-Authors: Charles H Sherman, John L Butler
    Abstract:

    Nonlinear transducer equations are formulated for the six major types of Electroacoustic Transducers (electrostatic, variable reluctance, moving coil, piezoelectric, electrostrictive, and magnetostrictive) in a common form using the various physical and mathematical similarities among the transduction mechanisms. The common nonlinear equation is solved approximately by perturbation analysis giving simple expressions and graphs for harmonic amplitudes caused by all the frequently occurring nonlinear mechanisms. The expressions and graphs can be applied to all the transducer types by using nonlinear parameters tabulated for each type. These results can facilitate diagnosis of the cause of measured harmonics, prediction of harmonics during design, and development of electrical drives to suppress harmonics.

  • nonlinear behavior of Electroacoustic Transducers
    Journal of the Acoustical Society of America, 1994
    Co-Authors: Charles H Sherman, John L Butler
    Abstract:

    An important goal of Electroacoustic transducer development has long been maximization of the acoustic output power for a given transducer size. This goal always encounters familiar material mechanical, electrical, magnetic or thermal limitations—all the ultimate effects of nonlinear behavior. However, other nonlinear effects, such as harmonic distortion and instability, are the practical operational limitation in some applications, making nonlinear analysis an essential part of the process. Most basic transduction mechanisms are strongly nonlinear and all have some nonlinearities. Fortunately, the nonlinearities in all Transducers have similar features and can often be represented in identical mathematical forms even when physically different. This study identifies the nonlinear features which are common to all major types of Transducers (electrostatic, variable reluctance, piezoelectric, electrostrictive, magnetostrictive, and moving coil). Recognizing these common features makes it possible to develop ...